Extracellular signal transduction effects morphology, migration and fate specification of cells during metazoan development and homeostasis. The highly conserved Wnt signaling pathway is instrumental in diverse processes such as embryonic axis formation and prevention of tumorigenesis. In the canonical Wnt pathway, ligand activation of receptors causes cytoplasmic accumulation and translocation of the Beta- catenin transcription factor. Nuclear Beta-catenin interacts with TCF/LEF, and activates transcription of specific target genes. In C. elegans this leads to the formation of the hermaphrodite vulva and possibly ventral cord neuron cell identity. Using this model organism and microarray analysis I will identify Beta- catenin targets and characterize Wnt pathway directed cell fate specification. Target candidates will be analyzed for consensus promoter elements, in situ expression patterns, and mutant phenotypes. This study will increase our understanding of Wnt signaling effects on differential gene expression and cell fate specification. Increased knowledge of cell fate specification mechanisms will aid in the development of preventative, diagnostic, and therapeutic treatments of defective cellular differentiation and development.